| 摘要 |
PROBLEM TO BE SOLVED: To provide a cold rolled steel sheet having both of high strength and excellent processability and a manufacturing method therefor.SOLUTION: There is provided a cold rolled steel sheet having a chemical composition containing, by mass%, C:0.05 to 0.30%, Si:0.5 to 2.5%, Mn:0.5 to 3.5%, P:0.100% or less, S:0.050% or less, sol.Al:0 to 1.00%, Cr:0 to 1.00%, Mo:0 to 0.30%, V:0 to 0.30%, B:0 to 0.0050%, Ca:0 to 0.003%, REM:0 to 0.003%, one or more selected from Ti:0.080% or less and Nb:0.050% or less and the balance of Fe with impurities and satisfying [0.003≤Ti+Nb≤0.100] and a metallic structure containing, by area%, bainite:50% or more, retained austenite:3.0% or more and ferrite:5.0% or more, where an average crystal particle diameter of the ferrite is 4.0 μm or less and a percentage of crystal particles existing neighboring to crystal particles of retained austenite having a crystal particle diameter of 0.2 to 1.0 μm is 50% or more.SELECTED DRAWING: None |
